House Interior Committee Chairman Morris K. Udall (D-Ariz.) has issued a strong statement of support for Dr. Everett Rhoades, the head of the Indian Health Service who was temporarily removed from his post because of allegations that he condoned favoritism shown his daughter in the awarding of a medical school scholarship.

Udall, whose committee has jurisdiction over the IHS, said in an Aug. 1 letter to Health and Human Services Secretary Margaret M. Heckler that his staff has investigated the allegations and concluded that "there is no credible evidence to show that Dr. Rhoades engaged in any improper activity as alleged, particularly with respect to his daughter's scholarship award."

Udall added, "The evidence that others engaged in improper actions within the Indian Health Service to the benefit of Dr. Rhoades or his family or friends is thin, at best."

In addition, Udall said, "To the extent that any actions engaged in by others within IHS tending to benefit Dr. Rhoades, his family or friends may have been improper, there is no evidence to show that Dr. Rhoades was contemporaneously aware of such action; that he motivated such acts; that he should have been aware of such actions, or that he acted in an improper manner when being made aware of such alleged improper actions."

In his letter, Udall suggested that Rhoades might have been a pawn in a Reagan administration campaign to oppose proposals by the Senate Select Committee on Indian Affairs and Udall's committee to elevate the IHS, now part of the Public Health Service, to a higher level within the PHS or to make it a separate HHS division headed by an assistant secretary.

Udall said his committee may find it necessary to hold hearings on how Heckler's department handled the Rhoades investigation. In the meantime, he asked that the department take no action in the case before Congress returns from its summer recess -- unless it decides to restore Rhoades to his post.

Rhoades, the first Indian to head the IHS, was temporarily assigned to another job June 21 while the HHS inspector general completed an investigation of the charges. A final report is expected soon.

According to the allegations, Rhoades' daughter Dorothy initially failed to receive a rating from two IHS examiners that was high enough to qualify her for an Indian health scholarship to Harvard University. It was alleged that a Rhoades aide first tried to get the cutoff grade lowered so she could qualify, then called in a third examiner who gave her a score high enough to bring her average above the cutoff level.

It was charged that IHS officials told Rhoades his subordinates were displaying favoritism toward his daughter but that he allowed the scholarship to go through. His daughter subsequently received $16,055 in scholarship aid in 1982 and $17,199 in 1983.

Rhoades has denied that he did anything improper. And several of his associates have contended that the third score was never used and that his daughter qualified anyway when the cutoff level was lowered routinely to use up money that was left over after the initial awards were made. Rhoades' attorney, Eugene R. Fidell, also contends that his client has not been allowed to use the full grievance procedure provided under PHS regulations.

Over the past two months, 11 high-level IHS officials were reported to have sent letters to Dr. James O. Mason, acting assistant secretary for health at HHS, praising Rhoades' professionalism, devotion to Indian health, and visits to hospitals to see patients and problems first-hand.